Busy weeks lately; apologies for the minimal bloggery, friends.
For this week’s Friday fold, I offer you a view of some of the outdoor decorations at our new house:
In the lower basket there is a cut and polished block of Castile Formation rock gypsum + limestone, showing varves that have been folded, apparently by hydration/dehydration volume changes of the gypsum/anyhdrite laminae:
This is from the State Line outcrop on the border of Texas and New Mexico in the legendary Permian Basin. I collected it during the epic “Border to Beltway” field trip that Joshua Villalobos of El Paso Community College and I co-led something like seven years ago…
Happy Friday to you. I’m headed into the field today to track down some mylonite. Be well.
I remember well the first time that I visited that outcrop in the late 1980s – truly a classic, and a rock sample that I always pass around in class when we discuss folding. Thanks!
Hah! I have a nice hunk of Castille Fm right next to my front door entryway. 🙂 Also from the famous state line outcrop.
That is a beautiful example of enterolithic folds in gypsum. However, if you keep it outside and have significant rain where you live (or water from the pot above) it will dissolve fairly rapidly, which would be a shame. On the other hand rillenkarren dissolved into the rock surface might look interesting.
Thanks for the tip – I noticed what I thought might be some shrink-swell desiccation fracturing on one side (not this one); this might also be due to having it outside. I’ll swap it out for something less soluble.
I am a frustrated geologist (that’s what I should have studied) I really appreciate your blog!